711.1 General Description This section includes the requirements for furnishing and placing turf reinforcement matting (TRM) over prepared areas according to the plans or as directed by the Engineer. 711. 1.01 Definitions General Provisions 101 through 150. 711.02 Related References
A.Standard Specifications Section 700—Grassing
B.Referenced Documents QPL 49 711.02 Submittals General Provisions 101 through 150. 711.2 Materials Use materials listed on QPL 49. TRM is designated Types 1, 2, 3, 4, 5, and 6 and ranges in allowable hydraulic shear stress from Type 1 to Type 6, Type 6 being the highest. Use a TRM type equal to or higher than the TRM type specified by the designer. All TRM types require permanent grass be sown concurrently with installation. Alternatively, in special cases dependent upon the soil’s vegetative-support quality and the growing season, the designer may specify only grass and mulch, or grass and a biodegradable rolled erosion control product for 0-3 psf (0-143 N/m2) shear stress conditions. ALLOWABLE HYDRAULIC SHEAR STRESS RANGES WITH VEGETATION Type 1 Type 2 Type 3 Type 4 Type 5 Type 6
0-2 psf (0-96
N/m2)
0-4 psf (0-191
N/m2)
0-6 psf (0-287
N/m2)
0-8 psf (0-382
N/m2)
0-10 psf (0-478
N/m2)
0-12 psf (0-574
N/m2) 1 Allowable hydraulic shear stress in the unvegetated condition = 2.0 psf (96 N/m2). Determine the allowable vegetated and unvegetated hydraulic shear stress for the TRM by using either of the independent laboratories of the Texas Transportation Institute (TTI) or the National Transportation Product Evaluation Program (NTPEP). Use the following large-scale test methods: ASTM D 6459 – 07 Standard Test Method for Determination of Rolled Erosion Control Product (RECP) Performance in Protecting Hillslopes from Rainfall-Induced Erosion ASTM D 6460 – 07 Standard Test Method for Determination of Rolled Erosion Control Product (RECP) Performance in Protecting Earthen Channels from Stormwater-Induced Erosion Ensure materials meet the following requirements.
A.Preformed TRM Use TRM with a web of mechanical or melt-bonded polymer nettings, monofilaments, or entangled fibers to form a dimensionally stable matrix. Bond the TRM with one of the following: • Polymer welding • Thermal fusion • Polymer fusion • Fibers placed between two high-strength, biaxially oriented nets bound by parallel-lock stitching with polyolefin, nylon, or polyester threads Use TRM with enough strength and elongation to limit stretching and maintain its shape before, during, and after installation under dry or wet conditions. Provide TRM with stabilized components that avoid ultraviolet degradation and are inert to chemicals normally encountered in a natural soil environment. Ensure the TRM conforms to the following minimum-value physical properties: Category Grab Tensile Strength lb./ft. (kN/m)1,2 UV Stability3 Allowable Hydraulic Shear Stress4 lb./ft.2 (N/m2) ASTM D 6818 ASTM D 43555 HEC 15, 2005 Type 1 125 (1.82) 80% 0-2 (0-96) Type 2 125 (1.82) 80% 0-4 (0-191) Type 3 125 (1.82) 80% 0-6 (0-287) Type 4 150 (2.19) 80% 0-8 (0-382) Type 5 175 (2.55) 80% 0-10 (0-478) Type 6 200 (2.92) 80% 0-12 (0-574) 1 Machine direction, ASTM D6818 2 In field conditions requiring high loading and/or high survivability requirements (e.g., the TRM having to bear heavy- equipment loading), tensile strength of 3,000 lb./ft. (44 kN/m ) or greater may be required 3 Percentage of strength of an unexposed sample retained 4 As calculated in accordance with the methods detailed in the FHWA HEC 15, 2005, document 5 Exposure in carbon arc light in accordance with ASTM D 822 and ASTM G 152 is required.
B.Stakes or Staples Use 1 in. by 3 in. (25 mm by 75 mm) wooden stakes made from sound stock cut in a triangular shape. Cut stakes 12 in. to 18 in. (300 mm to 450 mm) long depending on soil compaction. Use metal staples with the following characteristics: • 11- gauge steel • U shape • Legs at least 8 in. (200 mm) long • Crown 2 in. (50 mm) across When the construction plans specify deep anchors be used along with stakes or staples for zones of shear stress greater than 12 psf (574 N/m2) as an alternative to using riprap, follow the TRM manufacturer’s guidelines for anchor selection and installation procedures and provide the Engineer with the details of the recommended procedure. Use anchors listed on the QPL 49. 711.2.01 Delivery, Storage, and Handling General Provisions 101 through 150. 711.3 Construction Requirements 711.3.01 Personnel General Provisions 101 through 150. 711.3.02 Equipment General Provisions 101 through 150. 711.3.03 Preparation
A.Site Preparation Before protecting areas with TRM, prepare the area according to Section 700 with the following steps:
1.Bring the area to final grade.
2.Plow the area.
3.Lime the area.
4.Fertilize the area.
5.Grass the area. Provide a smooth, firm, and stable surface free of rocks, clods, roots, or other obstructions preventing the TRM from fully contacting the soil. 711.3.04 Fabrication General Provisions 101 through 150. 711.3.05 Construction
A.Installing TRM Do not use TRM in areas where rock crops out. Install the TRM either in ditches or on slopes according to the manufacturer’s instructions and provide the Engineer with the details of the recommended procedure. In the absence of specific instructions from the manufacturer, install the TRM according to the following requirements:
1.Ditches To install the TRM in ditches:
a.Cut a transverse trench 6 in. wide by 9 in. deep (150 mm wide by 225 mm deep) at the ends of the TRM.
b.Cut longitudinal, 4 in. (100 mm) deep anchor slots along each side of the TRM along the full length of the ditch and bury the TRM edges. The Engineer will require additional or deeper anchor slots or deep anchors for large volumes of water that cause high shear stress.
c.Roll out the center strip of TRM, starting at the lower end of the ditch.
d.Roll out each adjacent strip of TRM to overlap the preceding strip at least 3 in. (75 mm).
e.Overlap the ends of each TRM roll 3 ft. (1 m) with the upslope mat on top. Stretch the TRM to the bottom of the slot, folding it back and staking through two layers of material.
f.Stake each strip of TRM at 1 ft. (300mm) intervals in each anchor slot, with one stake serving the overlapped edges of adjoining strips.
g.Backfill and compact the slot.
h.Fold the TRM back over the slot and continue in the upstream direction (closed anchor slot).
i.Stake the TRM snugly in the longitudinal slots and at intervals a maximum of 5 ft. (1.5 m) along the ditch (open anchor slot).
j.Backfill and dress the longitudinal anchor slots. 711.3.06 Quality Acceptance General Provisions 101 through 150. 711.3.07 Contractor Warranty and Maintenance General Provisions 101 through 150. 711.4 Measurement TRM completed and accepted is measured for payment by the square yard (meter) of surface measured. 711.4.01 Limits Overlaps and anchor slots are incidental to the work and are not measured for payment. 711.5 Payment This work will be paid for at the Contract Price per square yard (meter) for TRM completed, in place, and accepted. Payment is full compensation for furnishing and installing the TRM according to this Specification. Preparation of the area and grassing will be paid for according to Section 700. Payment will be made under: Item No. 711 Turf reinforcement matting, Type ___ Per square yard (meter) 710.5.01 Adjustments General Provisions 101 through 150.
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Source: Standard Specifications for Construction of Transportation Systems, 2021 Edition. Pages 1394–1397 of 2,050. View official source ↗